The invention is based on an apparatus for automatically detecting a motor vehicle""s generator type, as generically defined by the preamble to the main claim.
Given the many types of motor vehicles, different generators with a different performance spectrum are required, which are controlled by suitable controllers. Thus in the event of repair of a controller, for instance, it can happen that the wrong generator type is installed, or that in the case of multi-generator operation, plugs are transposed, thus leading to corresponding problems, such as an overload on the controller or the generator connected to it. In this connection, a universal control unit for closed-loop control devices is known from European Patent Disclosure EP 0 376 983 B1 but this does not involve the detection of a special generator type for the motor vehicle but rather a universal control unit that can be adapted to the most various devices, such as engine control, ABS (Anti-lock Brake Systems) or ASR brake controllers (Traction Control). By polling the individual connections of a plug and by assigning different plugs differently, it is assured which unit is connected to the control device and which functions are necessary for controlling the connected unit. However, it appears unfavorable that with the units connected, the generator type cannot be ascertained by means of its behavior when a load is turned on.
The apparatus according to the invention having the characteristics of the body of the main claim has the advantage over the prior art that by simple provisions, namely the behavior of the generator when a load is turned on and off, the generator type can be detected. Complicated decoder circuits, type addressing operations, or mechanical encodings, for instance at the plug, are unnecessary. Nor is any additional hardware required, since the typical behavior of the generator can be detected by a simple program.
By the provisions recited in the dependent claims, advantageous refinements and improvements to the apparatus defined by the main claim are possible.
It is especially advantageous that the control unit performs the check of the generator type each time the internal combustion engine is started. This assures that a mistake that can happen at the repair facility, for instance, is detected early, so that damage to the generator, controller or other components cannot ensue.
It is considered particularly advantageous that an error signal is output, for instance visually or acoustically, to immediately tell the driver or a mechanic that an error has occurred.
The simplest method of type detection of the generator is considered to be that the set-point generator voltage is measured in its course as a function of time and stored in memory. Thus voltage changes can be most simply compared with the stored values.
Another good way of monitoring is to poll the signal at the terminal DF of the generator and compare it with the corresponding stored values. The current load of the generator can also be monitored at this terminal DF, so that in conjunction with the activated load and the voltage change, an unambiguous statement as to the generator type can be made.
It is also considered favorable that the voltage change is measured at the generator or at the terminal DF before and/or after the load is turned on. This is because when the load is turned on, the signal at the terminal DF increases relatively slowly, depending on the generator type and the load. When the load is turned off, conversely, the voltage rapidly fades, so that here the measurement is considered reliable after a predetermined waiting period has elapsed.
By measurements before the load is turned on, during the flow of electric current, and after the load is turned on, a reliable statement is advantageously obtained about the activated load as well.
To make it easy and fast to perform modifications, it is advantageous if as the memory, a nonvolatile memory is used that can be rewritten for new data, so that adaptations can be made quickly.